Positive electrodes and rechargeable lithium batteries including the same

Abstract

Provided is a positive electrode including a positive electrode current collector; and a positive electrode active material layer located on the collector and including a positive electrode active material, a copolymer binder, and an amine. The copolymer binder includes a first structural unit including a carboxyl group and a nonionic second structural unit, and the carboxyl group and the amine are present in a form of a salt. The positive electrode increases capacity while reducing production cost, thereby ensuring long cycle-life characteristics and improving high-voltage characteristics and high-temperature storage characteristics. The rechargeable lithium battery including the positive electrode may exhibit high initial charge/discharge capacity and efficiency even under high voltage driving conditions, and can achieve long cycle-life characteristics.

What is claimed is: 
     
         1 . A positive electrode comprising:
 a current collector; and   a positive electrode active material layer on the collector and including a positive electrode active material, a copolymer binder, and an amine;   wherein the copolymer binder comprises a first structural unit including a carboxyl group and a nonionic second structural unit, and   the carboxyl group and the amine are present in a form of a salt.   
     
     
         2 . The positive electrode as claimed in  claim 1 , wherein the positive electrode active material is represented by Chemical Formula 13: 
       
         
           
           
               
               
           
         
         wherein, in Chemical Formula 13, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, M 4  comprises one or more of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X comprises one or more of F, P, and S. 
       
     
     
         3 . The positive electrode as claimed in  claim 1 , wherein:
 the first structural unit is derived from a monomer including a carboxyl group, and   the monomer including a carboxyl group comprises at least one of a monocarboxylic acid and a derivative thereof, and dicarboxylic acid and a derivative thereof.   
     
     
         4 . The positive electrode as claimed in  claim 1 , wherein the copolymer binder comprises about 0.1 mol % to about 20 mol % of the first structural unit based on 100 mol % of the copolymer binder. 
     
     
         5 . The positive electrode as claimed in  claim 1 , wherein:
 the second structural unit is derived from a nonionic monomer, and   the nonionic monomer comprises at least one of an acrylic monomer and an imide monomer.   
     
     
         6 . The positive electrode as claimed in  claim 1 , wherein the amine comprises at least one of a primary amine, a secondary amine, a tertiary amine, an alkanol amine, an alkoxy amine, and a cyclic amine. 
     
     
         7 . The positive electrode as claimed in  claim 1 , wherein the copolymer binder is included in an amount in a range of about 10 wt % to about 30 wt % and the amine is included in an amount in a range of about 0.1 wt % to about 1.0 wt % based on the total 100 wt % of the positive electrode active material layer. 
     
     
         8 . The positive electrode as claimed in  claim 1 , wherein the positive electrode active material layer further comprises N-methylpyrrolidone. 
     
     
         9 . A method for manufacturing a positive electrode, the method comprising:
 (a) preparing a positive electrode composition comprising a positive electrode active material, a copolymer binder, a basic material including an amine group, and a volatile acidic material; and   (b) applying the positive electrode composition onto a current collector;   wherein the copolymer binder comprises a first structural unit including a carboxyl group and a nonionic second structural unit.   
     
     
         10 . A positive electrode composition, comprising:
 a positive electrode active material, a copolymer binder, an amine, and a volatile acidic material,   wherein the copolymer binder includes a first structural unit including a carboxyl group and a nonionic second structural unit.   
     
     
         11 . The positive electrode composition as claimed in  claim 10 , wherein:
 the first structural unit is derived from a monomer including a carboxyl group, and   the monomer including a carboxyl group comprises at least one of monocarboxylic acid and a derivative thereof, and dicarboxylic acid and a derivative thereof.   
     
     
         12 . The positive electrode composition as claimed in  claim 10 , wherein the copolymer binder comprises about 0.1 mol % to about 20 mol % of the first structural unit based on 100 mol % of the copolymer binder. 
     
     
         13 . The positive electrode composition as claimed in  claim 10 , wherein:
 the second structural unit is derived from a nonionic monomer, and   the nonionic monomer comprises at least one of an acrylic monomer and an imide monomer.   
     
     
         14 . The positive electrode composition as claimed in  claim 10 , wherein the amine comprises at least one of a primary amine, a secondary amine, a tertiary amine, an alkanol amine, an alkoxy amine, and a cyclic amine. 
     
     
         15 . The positive electrode composition as claimed in  claim 10 , wherein the volatile acidic material comprises at least one of oxalic acid, malic acid, and acetic acid. 
     
     
         16 . The positive electrode composition as claimed in  claim 10 , wherein the copolymer binder is included in an amount in a range of about 10 wt % to about 30 wt %, the amine is included in an amount in a range of about 0.1 wt % to about 1.0 wt %, and the volatile acidic material is included in an amount in a range of about 0.1 wt % to about 1.0 wt % based on 100 wt % of the positive electrode composition. 
     
     
         17 . The positive electrode composition as claimed in  claim 10 , wherein the positive electrode composition further comprises N-methylpyrrolidone. 
     
     
         18 . A rechargeable lithium battery, comprising:
 the positive electrode as claimed in  claim 1 ,   a negative electrode, and   an electrolyte.